Polymethine ethers

ABSTRACT

The invention provides novel compounds useful as intermediates for the production of polymethine compounds containing a desired counter ion with high purity and in high yields. 
 
Thus provided are polymethine ether compounds of the general formula (I) given below and a method of producing polymethine compounds which comprises bringing those compounds into contact with an acid.  
                 
 
In the above formula, R represents an alkyl group, an alkoxyalkyl group or an aryl group which may optionally be substituted, R 1  and R 2  each independently represents a hydrogen atom, halogen atom, nitro group, alkyl group, alkoxyalkyl group, alkoxy group or alkoxyalkoxy group and R 1  and R 2  may be bound to each other to form a ring; R 3  represents an alkyl group, which may optionally be substituted; L is an alkylene group required for the formation of a ring structure; and X represents a hydrogen atom, halogen atom, alkoxy group, aryloxy group, alkylthio group, arylthio group or substituted amino group.

TECHNICAL FIELD

The present invention relates to novel polymethine ether compounds and amethod of producing polymethine compounds utilizing the same.

BACKGROUND ART

In recent years, polymethine compounds have been in wide use, amongothers, as light-to-heat converting agents for optical recording media,for near-infrared absorbing filters or plate-making materials for whichlaser beams are to be utilized. These polymethine compounds generallyform a salt structure with a counter ion, and researches have been madeconcerning polymethine compounds improved in various ways with respectto the counter ion for the purpose of improving the solubility insolvents, the compatibility with resins, the durability and thesensitivity to laser beams.

For producing polymethine compounds containing a desired counter ionspecies, a method is known which comprises once synthesizing apolymethine compound containing a counter ion species relatively easy tosynthesize, for example a perchlorate ion, tetrafluoroborate ion orp-toluenesulfonate ion, dissolving the polymethine compound obtained anda compound containing the desired counter ion species in a solvent, forexample dimethylformamide (hereinafter referred to as “DMF”) to causecounter ion species interchange in the solvent, as described in Example1 in Japanese Kokai Publication 2000-302992, for instance.

Further, as is described in Example 1 in Japanese Kokai PublicationH11-1626, a synthetic method is known which comprises once synthesizinga polymethine compound containing a counter ion species relatively easyto synthesize, for example a perchlorate ion, tetrafluoroborate ion orp-toluenesulfonate ion, reacting the polymethine compound obtained withan alkali such as caustic soda to give an intermediate compound(hereinafter referred to as “hydroxy compound”) resulting fromelimination of the counter ion and having a structure represented by theformula (B) given below, and further reacting this hydroxy compound witha compound containing the desired counter ion.

(In the formula (B), R₁, R₂, R₃, L and X are as defined later hereinreferring to the formula (I).)

However, as regards the former method, the range of producible counterion species is limited and, further, the counter ion species exchange isincomplete and it is therefore difficult to obtain, by that method, thehigh-purity compounds containing a desired counter ion species in highyields. As for the latter method, on the other hand, the hydroxycompounds are very unstable and, therefore, this method of producingpolymethine compounds using those hydroxy compounds is not suitable asan industrial production method since the purity and yield of theproducts are low and a complicated purification process is required forobtaining high-purity products.

As a compound structurally close to the polymethine ether compounds ofthe invention, there is the compound (A) having the structure shownbelow as described in Dyes and Pigments, 46 (2000), 164. However, thereis no description about the use thereof, among others. If the compound(A) is used to produce the corresponding polymethine compound, thepolymethine compound obtained will show an absorption wavelength rangefairly longer (≧1000 nm) than the general-purpose semiconductor laserwavelength range and, further, the raw materials for the productionthereof are special and the production cost is increased accordingly,hence the industrial use value will be restricted.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide novel polymethineether compounds useful as intermediates for the production ofpolymethine compounds containing a desired counter ion.

As a result of various investigations made in an attempt to accomplishthe above object, the present inventors found that certain novelpolymethine ether compounds are stable and can be handled with ease andwhen they are reacted with an acid, high-quality polymethine compoundswith an acidic residue as the counter ion can be readily produced inhigh yields. This finding has now led to completion of the presentinvention.

In a first aspect, the present invention provides polymethine ethercompounds represented by the following general formula (I):

wherein R represents an alkyl group, an alkoxyalkyl group or an arylgroup which may optionally be substituted, R₁ and R₂ each independentlyrepresents a hydrogen atom, halogen atom, nitro group, alkyl group,alkoxyalkyl group, alkoxy group or alkoxyalkoxy group and R₁ and R₂ maybe bound to each other to form a ring; R₃ represents an alkyl group,which may optionally be substituted; L is an alkylene group required forthe formation of a ring structure; and X represents a hydrogen atom,halogen atom, alkoxy group, aryloxy group, alkylthio group, arylthiogroup or substituted amino group.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an IR absorption spectrum of the polymethine ether compound ofExample 1.

FIG. 2 is an IR absorption spectrum of the polymethine ether compound ofExample 2.

FIG. 3 is an IR absorption spectrum of the polymethine ether compound ofExample 3.

FIG. 4 is an IR absorption spectrum of the polymethine ether compound ofExample 4.

FIG. 5 is an IR absorption spectrum of the polymethine ether compound ofExample 5.

FIG. 6 is an IR absorption spectrum of the polymethine ether compound ofExample 6.

FIG. 7 is an IR absorption spectrum of the polymethine ether compound ofExample 7.

FIG. 8 is an IR absorption spectrum of the polymethine compound ofExample 8.

DETAILED DESCRIPTION OF THE INVENTION

In the following, the present invention is described in detail.

[Polymethine Ether Compounds]

First, the polymethine ether compounds represented by the generalformula (I) given below in accordance with the first aspect of theinvention are described.

In the above formula, R represents an alkyl group, an alkoxyalkyl groupor an aryl group which may optionally be substituted, R₁ and R₂ eachindependently represents a hydrogen atom, halogen atom, nitro group,alkyl group, alkoxyalkyl group, alkoxy group or alkoxyalkoxy group andR₁ and R₂ may be bound to each other to form a ring; R₃ represents analkyl group, which may optionally be substituted; L is an alkylene grouprequired for the formation of a ring structure; and X represents ahydrogen atom, halogen atom, alkoxy group, aryloxy group, alkylthiogroup, arylthio group or substituted amino group.(Substituent R)

When R is an alkyl group, it is preferably a straight or branched alkylgroup containing 1-8 carbon atoms, particularly preferably a straight orbranched alkyl group containing 1-4 carbon atoms. As examples, there maybe mentioned methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl,isohexyl, sec-hexyl, 2-ethylbutyl, n-heptyl, isoheptyl, sec-heptyl,n-octyl and 2-ethylhexyl.

When R is an alkoxyalkyl group, it is preferably one containing 2-8carbon atoms in total, particularly preferably one containing 2-4 carbonatoms in total. As examples, there may be mentioned methoxymethyl,2-methoxyethyl, 3-methoxypropyl, 2-ethoxymethyl, 2-ethoxyethyl,2-propoxyethyl and 2-butoxyethyl.

When R is an optionally substituted aryl group, it may be an optionallysubstituted phenyl group or an optionally substituted naphthyl group butpreferably is an optionally substituted phenyl group. Each substituentmay be an alkyl, amino, nitro, alkoxy or hydroxy group or a halogenatom, and preferably is an alkyl group containing 1-4 carbon atoms or analkoxy group containing 1-4 carbon atoms.

As examples of R when it is an alkyl-substituted phenyl, there may bementioned 2-methylphenyl, 3-methylphenyl, 4-methylphenyl,2,3-dimethylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl,2,5-dimethylphenyl, 2,6-dimethylphenyl, 2-ethylphenyl, 3-ethylphenyl,4-ethylphenyl, 2,3-diethylphenyl, 2,4-diethylphenyl, 3,4-diethylphenyl,2,5-diethylphenyl and 2,6-diethylphenyl.

As examples of R when it is an alkoxy-substituted phenyl, there may bementioned 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl,2,3-dimethoxyphenyl, 2,4-dimethoxyphenyl, 3,4-dimethoxyphenyl,2,5-dimethoxyphenyl and 2,6-dimethoxyphenyl.

(Substituents R₁ and R₂)

As the halogen atom represented by R₁ and/or R₂, there may be mentionedF, Cl, Br, 0 and so forth. However, Cl and Br are preferred, and Cl isparticularly preferred.

As for the alkyl group represented by R₁ and R₂, straight or branchedalkyl groups containing 1-8 carbon atoms are preferred, and straight orbranched alkyl groups containing 1-4 carbon atoms are particularlypreferred. As examples, there may be mentioned methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl,n-hexyl, isohexyl, sec-hexyl, 2-ethylbutyl, n-heptyl, isoheptyl,sec-heptyl, n-octyl and 2-ethylhexyl.

As for the alkoxyalkyl group represented by R₁ and R₂, alkoxyalkylgroups containing 2-8 carbon atoms in total are preferred, andalkoxyalkyl groups containing 2-4 carbon atoms in total are particularlypreferred. As examples, there may be mentioned 2-methoxyethyl,3-methoxypropyl, 4-methoxybutyl, 2-ethoxyethyl, 2-n-butoxyethyl,2-n-propoxyethyl, 2-isopropoxyethyl, 2-n-butoxyethyl, 3-ethoxypropyl,3-n-propoxypropyl, 4-ethoxybutyl, 4-n-propoxybutyl,2-methoxy-2-ethoxyethyl and 2-ethoxy-2-ethoxyethyl.

As for the alkoxy group represented by R₁ and R₂, straight or branchedalkoxy groups containing 1-8 carbon atoms are preferred, and straight orbranched alkoxy groups containing 1-4 carbon atoms are particularlypreferred. As examples, there may be mentioned methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, n-pentyloxy,isopentyloxy, neopentyloxy, n-hexyloxy, isohexyloxy, sec-hexyloxy,2-ethylbutoxy, n-heptyloxy, isoheptyloxy, sec-heptyloxy, n-octyloxy and2-ethylhexyloxy.

As for the alkoxyalkoxy group represented by R₁ and R₂, alkoxyalkoxygroups containing 2-8 carbon atoms in total are preferred, andalkoxyalkoxy groups containing 2-4 carbon atoms in total areparticularly preferred. Examples are 2-methoxyethoxy, 3-methoxypropoxy,4-methoxybutoxy, 2-ethoxyethoxy, 2-n-butoxyethoxy, 2-n-propoxyethoxy,2-isopropoxyethoxy, 2-n-butoxyethoxy, 3-ethoxypropoxy,3-n-propoxypropoxy, 4-ethoxybutoxy, 4-n-propoxybutoxy,2-methoxy-2-ethoxyethoxy and 2-ethoxy-2-ethoxyethoxy.

Preferred as R₁ and R₂ are a hydrogen atom, alkyl groups containing 1-8carbon atoms, alkoxyalkyl groups containing 2-8 carbon atoms in total,alkoxy groups containing 1-8 carbon atoms, alkoxyalkoxy groupscontaining 2-8 carbon atoms in total, or cyclic structures formed by R₁and R₂ bound to each other; particularly preferred are a hydrogen atom,alkyl groups containing 1-4 carbon atoms, alkoxyalkyl group containing2-4 carbon atoms in total, alkoxy groups containing 1-4 carbon atoms andalkoxyalkoxy groups containing 2-4 carbon atoms in total.

As the ring structure formed by R₁ and R₂ bound to each other, there maybe mentioned a benzene ring, hydrocarbon ring or oxygen-containingcyclic ring formed by R₁ and R₂ bound to each other, together with thebenzene ring carbon atoms bound to R₁ and R₂, respectively, preferably abenzene ring, a hydrocarbon ring containing 5-7 carbon atoms, or anoxygen-containing heterocycle containing 3-6 carbon atoms, morepreferably a benzene, cyclopentane or dioxolane ring. As examples, theremay be mentioned a benzene ring, cyclopentane ring, cyclohexane ring,cycloheptane ring, dioxolane ring and dioxane ring.

(Substituent R₃)

When R₃ is an unsubstituted alkyl group, it is preferably a straight orbranched alkyl group containing 1-18 carbon atoms, particularlypreferably a straight or branched alkyl group containing 1-8 carbonatoms. Examples are methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl,sec-hexyl, 2-ethylbutyl, n-heptyl, isoheptyl, sec-heptyl, n-octyl,2-ethylhexyl, n-decyl, n-dodecyl, n-pentadecyl and n-octadecyl.

As the substituted alkyl group represented by R₃, there may be mentionedalkoxyalkyl groups, sulfoalkyl groups and carboxyalkyl groups, amongothers. Alkoxyalkyl groups containing 2-8 carbon atoms in total arepreferred, and those containing 2-4 carbon atoms in total areparticularly preferred. As examples of the alkoxyalkyl groups, there maybe mentioned 2-methoxyethyl, 3-methoxypropyl, 4-methoxybutyl,2-ethoxyethyl, 2-n-butoxyethyl, 2-n-propoxyethyl, 2-isopropoxyethyl,2-n-butoxyethyl, 3-ethoxypropyl, 3-n-propoxypropyl, 4-ethoxybutyl,4-n-propoxybutyl, 2-methoxy-2-ethoxyethyl and 2-ethoxy-2-ethoxyethyl.

Preferred as R₃ are alkyl groups containing 1-8 carbon atoms oralkoxyalkyl groups containing 2-8 carbon atoms in total and, among them,alkyl groups containing 1-8 carbon atoms or alkoxyalkyl groupscontaining 2-4 carbon atoms in total are particularly preferred.

(Substituent L)

L is a substituted or unsubstituted alkylene group and forms a ringtogether with three carbon atoms, namely the carbon atom bound to X andthe carbon atoms on both sides thereof. Preferred as L are ethylene,propylene, butylenes, 2-oxapropylene, 2-thiapropylene, 2-methylpropyleneand 2-tert-butylpropylene and, among them, ethylene, propylene andbutylenes are particularly preferred.

(Substituent X)

The halogen atom represented by X includes F, Cl, Br and I, amongothers. Cl and Br are preferred, and Cl is particularly preferred.

The alkoxy group represented by X is preferably an alkoxy groupcontaining 1-8 carbon atoms, particularly preferably an alkoxy groupcontaining 1-4 carbon atoms. Examples are methoxy, ethoxy, propoxy,butoxy, pentoxy, hexyloxy, heptyloxy and octyloxy, among others.

The alkylthio group represented by X is preferably an alkylthio groupcontaining 1-8 carbon atoms, particularly preferably an alkylthio groupcontaining 1-4 carbon atoms. Examples are methylthio, ethylthio,propylthio, butylthio, pentylthio, hexylthio, heptylthio and octylthio,among others.

The aryloxy group represented by X is preferably a phenyloxy group,which may optionally have an alkyl group containing 1-8 carbon atoms asa substituent, particularly preferably a phneyloxy or methylphenyloxy.As examples, there may be mentioned phenyloxy, methylphenyloxy andtert-butylphenyloxy.

The arylthio group represented by X is preferably a phenylthio group,which may optionally have an alkyl group containing 1-8 carbon atoms asa substituent, particularly preferably phenylthio and methylphenylthio.As examples, there may be mentioned phenylthio, methylphenylthio andtert-butylphenylthio.

Preferred as the substituent(s) on the substituted amino grouprepresented by X are alkyl groups containing 1-8 carbon atoms and aphenyl group and, among them, alkyl groups containing 1-4 carbon atomsand a phenyl group are particularly preferred. As examples of X, theremay be mentioned methylamino, ethylamino, propylamino, butylamino,dimethylamino, diethylamino, dipropylamino, dibutylamino, phenylaminoand diphenylamino, among others.

Preferred as X are a hydrogen atom, Cl, Br, an alkoxy group containing1-8 carbon atoms, an alkylthio group containing 1-8 carbon atoms, aphenyloxy group optionally having an alkyl group(s) containing 1-8carbon atoms as a substituent(s), a phenylthio group optionally havingan alkyl group(s) containing 1-8 carbon atoms as a substituent(s), and asubstituted amino group optionally having an alkyl group(s) containing1-8 carbon atoms and/or a phenyl group(s) as a substituent(s).Particularly preferred are Cl, an alkoxy group containing 1-4 carbonatoms, an alkylthio group containing 1-4 carbon atoms, a phenyloxy groupoptionally having an alkyl group(s) containing 1-4 carbon atoms as asubstituent(s), a phenylthio group optionally having an alkyl group(s)containing 1-4 carbon atoms as a substituent(s) and a substituted aminogroup optionally having an alkyl group(s) containing 1-8 carbon atomsand/or a phenyl group(s) as a substituent(s).

(Specific Examples of the Compound of the Invention)

Preferred specific examples of the polymethine ether compounds of theinvention as represented by the general formula (I) are shown below.However, the compounds of the invention are not limited to these.

[Method of Producing the Polymethine Ether Compounds]

The polymethine ether compounds (I) of the invention can be produced,for example, by reacting a polymethine compound represented by thegeneral formula (II) given below with an alkali metal alkoxide or alkalimetal aryloxide represented by the general formula (III) given below inan organic solvent.

(In the formula, R₁ to R₃, L and X are as defined above and Z′⁻represents an acidic residue.)MOR  (III)(In the formula, M represents an alkali metal and R is as definedabove.)

In the above formula (II), Z′⁻ represents an acidic residue, for exampleF⁻, Cl⁻, Br⁻, I⁻, BrO₄ ⁻, ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻, SbF₆ ⁻, CF₃CO₂ ⁻, CH₃CO₂⁻, CF₃SO₃ ⁻, CH₃SO₃ ⁻, benzenecarbonate, benzenesulfonate,p-toluenesulfonate (hereinafter abbreviated as TsO⁻,naphthalenecarbonate, naphthalenedicarbonate, naphthalenesulfonate ornaphthalenedisulfonate. In particular, Cl⁻, Br⁻, I⁻, ClO₄ ⁻, BF₄ ⁻, PF₆⁻, SbF₆ ⁻, CF₃CO₂ ⁻, CF₃SO₃ ⁻, CH₃SO₃ ⁻, benzenecarbonate,benzenesulfonate and TsO⁻ are preferred, and ClO₄ ⁻, BF₄ ⁻ and TsO⁻ areparticularly preferred.

In the above reaction, M is an alkali metal such as sodium or potassium.

As the organic solvent, there may be mentioned, among others, alcoholssuch as methanol, ethanol, n-propanol, isopropanol and n-butanol, etherssuch as tetrahydrofuran and dioxane, esters such as methyl acetate,ethyl acetate and butyl acetate, aromatic hydrocarbons such as benzene,toluene and xylene, halogenated hydrocarbons such as dichlormethane,trichloromethane, dichloroethane and trichloroethane, and aprotic polarsolvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide.

As for the quantity ratio between the compound represented by thegeneral formula (II) and the compound represented by the general formula(III), the latter is generally used in an amount of about 1-30 moles,preferably about 2-10 moles, per mole of the former.

The organic solvent is generally used in an amount of about 2-30 liters,preferably about 5-20 liters, per mole of the compound represented bythe general formula (II).

The above reaction can smoothly proceed generally at about 0-100° C.,preferably at about 10-70° C., and will be generally complete in severalminutes to about 10 hours.

After the reaction, the desired product can be readily isolated bycollection by filtration, followed by washing. It can be purified withease by the conventional purifying means, such as recrystallizationand/or column separation.

The above-mentioned compound represented by the general formula (II) canbe synthesized by the method described in Japanese Kokai Publication2000-226528, for instance.

[Method of Producing the Final Product Polymethine Compounds]

The polymethine compounds represented by the formula (IV):

(wherein R₁ to R₃, L and X are as defined above general formula (I) andZ⁻ represents an acidic residue) which have a desired Z⁻, can then beproduced from the ether compounds of general formula (I), for example,by reacting an ether compound represented by the formula (I) with anacid containing the desired Z in an organic solvent.

As Z⁻, there may be mentioned, among others, halogen ions such as F⁻,Cl⁻, Br⁻ and I⁻, alkylsulfonate ions such as CH₃SO₃ ⁻, CF₃SO₃ ⁻ andC₂H₅SO₃ ⁻, arylsulfonate ions such as benzenesulfonate andp-toluenesulfonate (hereinafter abbreviated as TsO⁻),naphthalenesulfonate ions such as 2-naphthalenesulfonate ion,1-hydroxy-4-naphthalenesulfonate ion and 2,3-naphthalenedisulfonate ion,alkylcarboxylate ions such as CH₃CO₂ ⁻, C₂H₅CO₂ ⁻, C₃H₇CO₂ ⁻, CF₃CO₂ ⁻and C₂F₅CO₂ ⁻, arylcarboxylate ions such as benzoate ion and3-hydroxybenzoate ion, naphthalenecarboxylate ions such as2-naphthalenecarboxylate ion, 1-hydroxy-4-naphthalenecarboxylate ion and2,3-naphthalenedicarboxylate ion, organoboron ions such as triphenylbutyl borate ion and tetraphenyl borate ion, organometal complex ionssuch as benzenedithiol nickel complex ion, BrO₄ ⁻, ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻,SbF₆ ⁻, etc.

The organic solvent includes alcohols such as methanol, ethanol,n-propanol, isopropanol and n-butanol, ethers such as tetrahydrofuranand dioxane, esters such as methyl acetate, ethyl acetate and butylacetate, aromatic hydrocarbons such as benzene, toluene and xylene,halogenated hydrocarbons such as dichlormethane, trichloromethane,dichloroethane and trichloroethane, and aprotic polar solvents such asdimethylformamide, dimethylacetamide and dimethyl sulfoxide.

The desired Z-containing acid may be a proton donor acid or an electronacceptor acid.

The desired Z-containing proton donor acid includes, among others,hydrohalic acids such as HF, HCl, HBr and HI, alkylsulfonic acids suchas CH₃SO₃H, CF₃SO₃H and C₂H₅SO₃H, arylsulfonic acids such asbenzenesulfonic acid and p-toluenesulfonic acid, naphthalenesulfonicacids such as 2-naphthalenesulfonic acid,1-hydroxy-4-naphthalenesulfonic acid and 2,3-naphthalenedisulfonic acid,alkylcarboxylic acids such as CH₃CO₂H, C₂H₅CO₂H, C₃H₇CO₂H, CF₃CO₂H andC₂F₅CO₂H, arylcarboxylic acids such as benzoic acid and 3-hydroxybenzoicacid, naphthalenecarboxylic acids such as 2-naphthalenecarboxylic acid,1-hydroxy-4-naphthalenecarboxylic acid and 2,3-naphthalenedicarboxylicacid, HBrO₄, HClO₄, HBF₄, HPF₆ and HSbF₆.

The desired Z-containing electron acceptor acid includes, among others,organoborate salts such as triphenyl butyl borate salts and tetraphenylborate salts, organic dithiol metal complex salts such as benzenedithiolnickel complex salts, zinc chloride and aluminum chloride.

As for the quantity ratio between the compound represented by thegeneral formula (I) and the acid containing the desired Z, the latter isgenerally used in an amount of about 0.5-5 moles, preferably about 1-2moles, per mole of the former.

The organic solvent is generally used in an amount of about 2-30 liters,preferably about 5-20 liters, per mole of the compound represented bythe general formula (I).

The above reaction proceeds smoothly generally at a temperature nothigher than 100° C., preferably 10-50° C., and will be completegenerally in several minutes to about 10 hours.

After the reaction, the desired product can be readily isolated bycollection by filtration, followed by washing. Further, it can bepurified with ease by the conventional means, for example byrecrystallization and/or column separation.

EXAMPLES

The following examples illustrate the present invention morespecifically. These examples are, however, by no means limitative of thescope of the invention.

Example 1 Production of a Polymethine Ether Compound (Specific ExampleCompound (1))

A compound represented by the general formula (II) (each of R₁ andR₂=hydrogen atom, R₃=methyl, L=propylene, X=Cl, Z′⁻=ClO₄ ⁻; 3.79 g) and1.76 g of a compound represented by the general formula (III) (M=Na,R=methyl) were added to 150 ml of methanol, the mixture was stirred at20-25° C. for 3 hours, the resulting crystalline precipitate wasfiltered off, washed with methanol and recrystallized from acetone togive 2.68 g of Specific Example Compound (1).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₃₃H₃₉ClN₂O): MW = 515.13 C H N Calculated(%) 76.94 7.63 5.44 Found (%) 76.88 7.69 5.48 Melting point (° C.):159-162° C. (decomposition)

An IR spectrum of the compound obtained is shown in FIG. 1.

Example 2 Production of a Polymethine Ether Compound (Specific ExampleCompound (2))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (III) as used was the one with M=Na andR=ethyl (2.21 g), to give 2.82 g of Specific Example Compound (2).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₃₄H₄₁ClN₂O): MW = 529.15 C H N Calculated(%) 77.17 7.81 5.29 Found (%) 77.08 7.79 5.26 Melting point (° C.):150-153° C. (decomposition)

An IR spectrum of the compound obtained is shown in FIG. 2.

Example 3 Production of a Polymethine Ether Compound (Specific ExampleCompound (6))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (II) as used was the one with each of R₁and R₂=hydrogen atom, R₃=n-propyl, L=propylene, X=Cl, Z′⁻=ClO₄ ⁻ (4.16g), to give 2.80 g of Specific Example Compound (6).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₃₇H₄₇ClN₂O): MW = 571.23 C H N Calculated(%) 77.80 8.29 4.90 Found (%) 77.88 8.35 4.92 Melting point (° C.):97-100° C.

An IR spectrum of the compound obtained is shown in FIG. 3.

Example 4 A polymethine Ether Compound (Synthesis of Specific ExampleCompound (12))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (II) as used was the one withR₁=5-methoxy, R₂=7-methyl, R₃=methoxyethyl, L=propylene, X=Cl, Z′⁻=BF₄ ⁻(4.86 g) and that the compound of general formula (III) as used was theone with M=Na and R=ethyl (2.21 g), to give 2.90 g of Specific ExampleCompound (12).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₄₂H₅₇ClN₂O₅): MW = 705.37 C H N Calculated(%) 71.52 8.15 3.97 Found (%) 71.36 8.19 3.94 Melting point (° C.):143-145° C.

An IR spectrum of the compound obtained is shown in FIG. 4.

Example 5 A polymethine Ether Compound (Synthesis of Specific ExampleCompound (16))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (II) as used was the one with R₁ andR₂=5,6-methylenedioxy, R₃=methyl, L=propylene, X=Cl, Z′⁻=ClO₄ ⁻ (4.37g), to give 2.83 g of Specific Example Compound (16).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₃₅H₃₉ClN₂O₅): MW = 603.15 C H N Calculated(%) 69.70 6.52 4.64 Found (%) 59.56 6.49 4.58 Melting point (° C.):175-177° C.

An IR spectrum of the compound obtained is shown in FIG. 5.

Example 6 A polymethine Ether Compound (Synthesis of Specific ExampleCompound (17))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (II) as used was the one with R₁ andR₂=5,6-benzo, R₃=methyl, L=propylene, X=Cl, Z′⁻=TsO⁻ (4.91 g), to give2.54 g of Specific Example Compound (17).

The elemental analysis data and melting point of this compound were asfollows. Elemental analysis (C₄₁H₄₃ClN₂O): MW = 615.25 C H N Calculated(%) 80.04 7.04 4.55 Found (%) 80.04 7.05 4.61 Melting point (° C.):184-187° C.

An IR spectrum of the compound obtained is shown in FIG. 6.

Example 7 A polymethine Ether Compound (Synthesis of Specific ExampleCompound (22))

The procedure of Example 1 was followed in the same manner except thatthe compound of general formula (II) as used was the one with each of R₁and R₂=hydrogen atom, R₃=methyl, L=ethylene, X=Cl, Z′⁻=ClO₄ ⁻ (3.70 g),to give 2.62 g of Specific Example Compound (22). Elemental analysis(C₃₂H₃₇ClN₂O): MW = 501.10 C H N Calculated (%) 76.70 7.44 5.59 Found(%) 76.62 7.50 5.59 Melting point (° C.): 205-207° C.

An IR spectrum of the compound obtained is shown in FIG. 7.

Example 8 Synthesis of a Polymethine Compound

Specific Example Compound (12) (5.00 g) was added to 50 ml of methanol,and 15 ml of a methanol solution containing 3.00 g ofpentafluoropropionic acid was added dropwise thereto with stirring at25-30° C. After 2 hours of stirring at the same temperature, themethanol was distilled off from the reaction mixture using anevaporator, and 50 ml of ethyl acetate was then added to the residue.The resulting crystalline precipitate was filtered off, washed withethyl acetate and dried to give 4.98 g of a compound having thestructure given below (yield: 85.2%).

The elemental analysis data, melting point, absorption maximumwavelength (λmax) and gram extinction coefficient (eg) of this compoundwere as follows. Elemental analysis (C₄₃H₅₂ClF₅N₂O₆): MW = 823.3 C H NCalculated (%) 62.73 6.37 3.40 Found ( % ) 62.81 6.40 3.38 Melting point(° C.): 198-199° C. λmax: 822 nm (diacetone alcohol solution) εg: 2.75 ×10⁵ ml/g · cm

An IR spectrum of the compound obtained is shown in FIG. 8.

Comparative Example 1 A Hydroxy Compound and Production of a PolymethineCompound Using the Same

As described in Example 1 in Japanese Kokai Publication H11-1626, 15.0 gof a compound of general formula (II) with R₁=5-methoxy, R₂=7-methyl,R₃=methoxyethyl, L=propylene, X=Cl, Z′⁻=BF₄ ⁻ was added to 150 ml ofDMF, and the mixture was stirred at 20-25° C. for 0.5 hour to effectdissolution. The solution was green, and the λmax of the DMF solutionwas 824 nm. To this DMF solution was added 4.8 g of a 50% aqueoussolution of caustic soda, followed by 1.0 hour of stirring at 25-30° C.The color of the DMF solution changed from green to yellowish brown (theλmax of the DMF solution changed to 434 nm and the absorption at 824 nmdisappeared).

The reaction mixture was poured into 1500 g of ice water, and theresulting crystalline precipitate was filtered off, washed with waterand dried to give 12.51 g of an ocher compound.

This compound gave the following elemental analysis data and wasidentified as a hydroxy compound of the formula (B) given hereinabove.Elemental analysis (C₄₀H₅₃ClN₂O₅): MW = 677.31 C H N Calculated (%)70.93 7.89 4.14 Found (%) 70.48 7.99 4.19

A 3.39-g portion of the hydroxy compound obtained was dissolved in 35 mlof methanol, and 15 ml of a methanol solution containing 2.12 g ofpentafluoropropionic acid was added dropwise thereto with stirring at25-30° C. After 2 hours of stirring at the same temperature, themethanol was distilled off from the reaction mixture using anevaporator, and 35 ml of ethyl acetate was added to the residue. Theresulting crystalline precipitate was filtered off, washed with ethylacetate and dried to give 2.28 g (yield: 55.3%) of a compound having thesame structure as the product obtained in Example 8.

The absorption maximum wavelength (λmax) and gram extinction coefficient(eg) of this compound were as follows.

λmax: 822 nm (diacetone alcohol solution)

εg: 0.98×10⁵ ml/g·cm

As compared with Example 8 in which a polymethine ether compound of theinvention was used, the yield of the polymethine compound was low andthe purity of the compound obtained was low (εg ratio relative to thecompound of Example 8: 0.36).

INDUSTRIAL APPLICABILITY

The compounds of the invention are useful intermediates for theproduction of polymethine compounds containing a desired counter ionwith high purity and in high yields.

The novel polymethine ether compounds are stable and can be handled withease and, when reacted with an acid, can give high-quality polymethinecompounds with the acidic residue as the counter ion in high yields.

1. A polymethine ether compound represented by the general formula (I):

wherein R represents an alkyl group, an alkoxyalkyl group or an arylgroup which may optionally be substituted, R₁ and R₂ each independentlyrepresents a hydrogen atom, halogen atom, nitro group, alkyl group,alkoxyalkyl group, alkoxy group or alkoxyalkoxy group and R₁ and R₂ maybe bound to each other to form a ring; R₃ represents an alkyl group,which may optionally be substituted; L is an alkylene group required forthe formation of a ring structure; and X represents a hydrogen atom,halogen atom, alkoxy group, aryloxy group, alkylthio group, arylthiogroup or substituted amino group.
 2. A polymethine ether compoundaccording to claim 1, wherein R is an alkyl group containing 1-8 carbonatoms, an alkoxyalkyl group containing 2-8 carbon atoms in total or aphenyl which may optionally have an alkyl group containing 1-4 carbonatoms or an alkoxy group containing 1-4 carbon atoms as a substituent,R₁ and R₂ each is a hydrogen atom, an alkyl group containing 1-8 carbonatoms, an alkoxyalkyl group containing 2-8 carbon atoms in total or analkoxy group containing 1-8 carbon atoms or R₁ and R₂ are bound to eachother and form, together with the benzene ring carbon atoms bound to R₁and R₂, respectively, a benzene ring, a hydrocarbon ring containing 5-7carbon atoms or an oxygen-containing heterocycle containing 3-6 carbonatoms, and R₃ is an alkyl group containing 1-18 carbon atoms or analkoxyalkyl group containing 2-8 carbon atoms in total.
 3. A polymethineether compound according to claim 1, wherein L is an alkylene groupcontaining 2-4 carbon atoms.
 4. A polymethine ether compound accordingto claim 1, wherein X is a hydrogen atom, Cl, Br, an alkoxy groupcontaining 1-8 carbon atoms or a diphenylamino.
 5. A method of producingpolymethine compounds represented by the general formula (IV) givenbelow which comprises reacting a polymethine ether compound representedby the general formula (I) given above with an acid:

wherein R₁ and R₂ each independently represents a hydrogen atom, halogenatom, nitro group, alkyl group, alkoxyalkyl group, alkoxy group oralkoxyalkoxy group and R₁ and R₂ may be bound to each other to form aring; R₃ represents an alkyl group, which may optionally be substituted;L is an alkylene group required for the formation of a ring structure; Xrepresents a hydrogen atom, halogen atom, alkoxy group, aryloxy group,alkylthio group, arylthio group or substituted amino group; and Z⁻represents an acidic residue.
 6. A polymethine ether compound accordingto claim 2, wherein L is an alkylene group containing 2-4 carbon atoms.7. A polymethine ether compound according to claim 2, wherein X is ahydrogen atom, Cl, Br, an alkoxy group containing 1-8 carbon atoms or adiphenylamino.
 8. A polymethine ether compound according to claims 3,wherein X is a hydrogen atom, Cl, Br, an alkoxy group containing 1-8carbon atoms or a diphenylamino.